Importantly, in endometrium-related uterine and ovarian carcinomas exhibiting the highest mutation efficiency of ARID1A, it appears that dependence on ARID1A is also observed in cancers carrying ARID1A mutations, suggesting that ARID1A may exert pro-tumor functions in certain subtypes of these cancers, where mutation of ARID1A may have antitumor activity. The gene discussed is ARID1A; the disease is ovarian carcinoma.